On 2/10/26 11:08, Jerry D wrote:
Dear all, as requested,
See attached patch 5 of 13
I've got some comments on the documentation part:
diff --git a/gcc/fortran/invoke.texi b/gcc/fortran/invoke.texi
index 549c45032fd..6e8e13a982b 100644
--- a/gcc/fortran/invoke.texi
+++ b/gcc/fortran/invoke.texi
@@ -104,6 +104,7 @@ one is not the default.
* Interoperability Options:: Options for interoperability with other
languages.
* Environment Variables:: Environment variables that affect @command{gfortran}.
+* Shared Memory Coarrays:: Multi process shared memory coarray support.
I think you need to s/shared memory coarrays/shared-memory coarrays/g
per the usual rule that adjective phrases are hyphenated when they
appear before the noun they modify.
I also think "multiprocess" -- one word, no hyphen -- is preferred to
either "multi process" or "multi-process". At least I see
"multiprocessing" and "multiprocessor" in other places in the GCC
manuals, and as preferred terminology on Wikipedia.
Other than that....
@end menu
@node Option Summary
@@ -2305,3 +2306,56 @@ variables.
@xref{Runtime}, for environment variables that affect the
run-time behavior of programs compiled with GNU Fortran.
@c man end
+
+@node Shared Memory Coarrays
+@section Shared Memory Coarrays
+
+@c man begin SHARED MEMORY COARRAYS
+
+@command{gfortran} supplies a runtime library for running coarray enabled
coarray-enabled
+programs using a shared memory multi process approach. The library is supplied
shared-memory multiprocess
+as a static link library with the @command{libgfortran} library and is fully
library, and...
+compatible with the ABI enabled when @command{gfortran} is called with
s/called/invoked/
+@code{-fcoarray=lib}. The shared memory coarray library then just needs to be
s/@code/@option
+linked to the executable produced by @command{gfortran} using
+@code{-lcaf_shmem}.
here too.
I'd like to see that last sentence put in the active voice: "Link the
shared-memory coarray library to your executable using.... "
+
+The library @code{caf_shmem} can only be used on architectures that allow
+multiple processes to use the same memory at the same virtual memory address in
+each process' memory space. This is the case on most Unix and Windows based
Unix- and Windows-based
+systems.
+
+The resulting executable can be started without any driver and does not provide
+any additional command line options. Limited control is possible by
+environment variables:
That paragraph is confusing. How about just saying
You can control some aspects of the library behavior at run time using
environment variables.
+
+@env{GFORTRAN_NUM_IMAGES}: The number of images to spawn when running the
+executable. Note, there will always be one additional supervisor process,
which
s/will always be/is always/
+does not participate in the computation, but is only responsible for starting
+the images and catching any (ab-)normal termination. When the environment
+variable is not set, then the number of hardware threads reported by the OS
will
+be taken.
s/will be taken/is used/
Over-provisioning is possible. The number of images is limited only
+by the OS and the size of an integer variable on the architecture the program
is
+to be run on.
s/to be run on/running on/
+
+@env{GFORTRAN_SHARED_MEMORY_SIZE}: The size of the shared memory segment made
+available to all images is fixed and needs to be set at program start. It can
+not grow or shrink.
s/can not/cannot/
The size can be given in bytes (no suffix), kilobytes
+(@code{k} or @code{K} suffix), megabytes (@code{m} or @code{M}) or gigabytes
+(@code{g} or @code{G}). If the variable is not set, or not parseable, then on
+32-bit architectures 2^28 bytes and on 64-bit 2^34 bytes are choosen. Note,
s/choosen/chosen/
+although the size is set, most modern systems do not allocate the memory at
+program start. This allows to choose a shared memory size larger than
available
s/allows to choose/allows you to choose/
+memory.
+
+Warning: Choosing a large shared memory size may produce large coredumps!
s/coredumps/core dumps/
+
+The shared memory coarray library internally uses some additional environment
+variables, which will be overwritten without notice or may result in failure to
s/will be/are/
+start. These are: @code{GFORTRAN_IMAGE_NUM}, @code{GFORTRAN_SHMEM_PID} and
+@code{GFORTRAN_SHMEM_BASE}. It is strongly discouraged to use these variables.
+Special care needs to be taken, when one coarray program starts another coarray
s/taken,/taken/
+program as a child process. In this case it is the spawning process'
+responsibility to remove above variables from the environment.
+
+@c man end
-Sandra
